Apparatus for and method of closing bag bottoms



R. R. WEIS 3,156,165

APPARATUS FOR AND METHOD OF CLOSING BAG BOTTOMS Nov. 10, 1964 s Sheets-Sheet 1 Filed Jan. 29, 1962 IN VEN TOR. P000452, xvi/.5

AT TO/PNEVS' Nov. 10, 1964 R. R. WEIS 3,156,155

APPARATUS FOR AND METHOD OF CLOSING BAG BOTTOMS Filed Jan. 29, 1962 s Sheets-Sheet 2 f asy IN'VENTOR. Pl/DOLF R 415/6 A T TORNE K5 Nov. 10, 1964 R. R. WEIS 3,156,165

APPARATUS FOR AND METHOD OF CLOSING BAG BOTTOMS Filed Jan. 29, 1962 3 Sheets-Sheet 3 F/G 4 INVENTOR. P11000 P. k/i/' A T TORNE VS United States Patent Rudolf R. Weis, Antioch, Calif., assignor to Crown Zellerhach ilorporation, San Francisco, Calif, a corporation of Nevada Filed Jan. 29, 1962, Ser. No. 169,301 8 @laims. (ill. 9327) This invention relates to flap-folding apparatus, and more particularly to an apparatus for and method of closing bag bottoms.

In the manufacture of bags, and considering in particular paper grocery bags of the self-opening type as a specific article with which the invention is useful, such bags are made from continuous flat stock drawn from a parent roll and the stock is first formed upon a mandrel into an endless tube and is secured in this tubular configuration by adhesively joining its overlapping longitudinal edge portions. The endless tube is cut into appropriate lengths, called bag tubes, and folded into a generally planar configuration with the bottom end thereof having its longitudinal edge portions folded inwardly which in part provide such bottom with leading and trailing flaps. Subsequently, a pattern of adhesive is applied to the bag bottom, and the flaps are folded inwardly thereagainst to close the same. Such bag-forming operations are continuous and are performed at high speeds with all of the various steps occurring While the bag tube is moving along the longitudinal axis thereof.

With respect to the present invention, the equipment employed in forming the bag tubes and providing the bottoms thereof with leading and trailing flaps may be wholly conventional. The apparatus generally used for applying adhesive to the bag bottom and for closing the flaps thereof is often referred to as a bag-bottoming machine, and in such machine, the trailing flap is first folded forwardly to adhesively secure the same to the underlying or inwardly disposed longitudinal edge portions of the bag bottom, and subsequent thereto the leading flap is folded rearwardly to adhesively secure it to the trailing flap and underlying longitudinal edge portions of the bag bottom to complete or close the same.

The bag-bottoming machinery now in commercial use effects the forward folding of the trailing flap of the bag bottom by endless chains that engage each such flap as the bags are advanced along a generally circular path by a rotating cylindrical drum that comprises a part of the bag-bottoming machinery. Such apparatus for folding the trailing flaps of the bag tubes has serious disadvantages even though it is in wide commercial use; and because of this, attempts have been made to eliminate the flap-folding chains, improve the folding technique, and increase the quality of the bag bottom. An example of a prior effort in this respect is disclosed in Evers Patent No. 2,691,329, but so far as is known such prior attempts have not in general had commercial acceptability.

Accordingly, an object of the present invention is to provide an improved arrangement for folding the trailing flap of a bag tube as the tube is being continuously advanced along an arcuate path by the rotatable drum of a bag-bottoming machine, and which eliminates the use of high speed endless chains, reduces the noise level incident to the use of such chains, obviates the hazards to personnel inherent in the use of such chains, and sharply reduces general maintenance costs, down time, jam-ups and damage to the equipment-particularly the drive gear-that often results from the use of the folding chains. Another object of the invention is that of providing a flap-folding mechanism that is susceptible to a high rate of production, and that is clean (in contrast to end less chains) because it has a sealed-in-oil mechanism which also reduces lubrication requirements.

Still another object is in the provision of an improved flap-folding apparatus that is mechanically simple, economical, positive in its function, and that operates in synchronism with the rotatable drum of a bag-bottoming machine so that its flap-folding rate is automatically adjusted to the rate of advancement of bag tubes by the drum. Yet another object is to provide apparatus for folding the trailing flap of a bag tube, and which is adapted to readily accommodate bags of various size which thereby simplifies changeover or adjustment of the equipment from one bag size to another, and which is characterized by being relatively small which enables the same to be employed within narrow confines.

A further object of the invention is to provide irnproved flap-folding apparatus especially useful for folding the trailing flap of a bag tube and which has a rotatable flap folder that is rotated with a varying velocity pattern of angular acceleration in the direction toward engagement with a flap and of angular deceleration sub sequent thereto, and in which the average angular velocity thereof is timed with the rate of advancement thereto of articles having a flap to be folded so that the flap of each successive article is engaged by the flap foldersuch velocity pattern permitting the flap folder to have relatively small perimetric dimensions since the arcuate path described by the rotatable flap folder can be made quite small without losing the requisite average rotational velocity. Still a further object is to provide flap folder apparatus of the character described in which the rotatable flap folder thereof has a spacially fixed axis of rotation with the result that a single continuous plane is described by the rotational movement thereof, and in which the flap folder is relatively wide which increases the period of engagement thereof with each flap.

Yet a further object is to provide a method of closing the bottom of a bag tube, and in which the trailing flap of such bag tube is folded forwardly and is wiped or pressed against the underlying bag bottom from the center or an intermediate location toward the longitudinal edge portions while progressively increasing the area of such flap which is pressed into engagement with the underlying bag bottom, whereby a smooth bottom closure free of wrinkles and other irregularities is obtained. Additional objects and advantages of the invention will become apparent as the specification develops.

An embodiment of the invention is illustrated in the accompanying drawings, in which FIGURE 1 is a side view in elevation, largely diagrammatic, showing the improved flap-folding apparatus in association with a bag-bottoming machine;

FIGURE 2 is a vertical sectional view, partly in elevation, taken along the plane 2-2 of FIGURE 1 but in which the flap folder has been advanced by approximately 270 to illustrate the same in a position of substantially zero acceleration;

FiGURE 3 is a vertical sectional view taken along the plane 33 of FIGURE 2;

FIGURE 4 is a vertical sectional view taken along the plane 4-4 of FIGURE 3, and in which the relative positions of the flap folders are shown by broken lines, as is an alternate position of the drive mechanism;

FIGURE 5 is a perspective view of a bag showing the bottom thereof after a pattern of adhesive has been ap plied thereto and before the trailing and leading flaps have been folded;

FIGURE 6 is a perspective view similar to that of FIGURE 5, but illustrating the forward folding of the trailing flap by the flap folders and showing engagement of the leading fiap with the stationary folding plow of a bag-bottoming machine; and

FIGURE 7 is a perspective view showing the bag after the bottom thereof has been completely closed.

The exemplary apparatus shown in FIGURE 1 is essentiaily a bag-bottoming machine, and includes a generally cylindrical drum 10 mounted for rotation about an axis defined by a shaft or axle 11 extending through the drum. The drum 10 is equipped with a ring gear 12, and is rotated in a clockwise direction (as viewed in FIGURE 1) by a drive gear 13 that engages the ring gear 12 and is driven by a motor 14. A succession of flap-equipped articles is fed to the drum it by a conveyor, shown diagrammatically at 15, which may be completely conventional and, for example, may be an endless belt entrained at opposite ends thereof about drive and idler pulleys. It will be apparent that guide structure, usually in the form of rollers, will be operatively arranged with the conveyor and drum to direct such articles onto the cylindrical surface of the drum, but such structure has not been illustrated for purposes of simplifying the drawings and because they do not per se form a part of the present invention.

The drum 10 in its rotary movement advances such articles through an adhesive-applying station at which a pattern of adhesive is applied to each such article. in the drawings, such adhesive station is defined by an applicator 16 rotatable about an axis defined by a shaft 17 supported at opposite ends thereof by brackets 18. The adhesive applicator 16 is equipped with a gear 19 that meshes with the ring gear 12 of the drum it so that the adhesive applicator is rotated in synchronism with the drum. The applicator 16 may be conventional and may be one of the well known, commercially available types.

Following the adhesive-applying station is a flap-folding station defined by fiap-flolding apparatus generally designated with the numeral 20, and the drum 10 is adapted to advance articles thereto after moving the same through the adhesive-applying station. After the flaps of each article are folded, the drum discharges the articles onto a conveyor diagrammatically indicated at 21, and such conveyor may be of any suitable type. By way of further explanation, the conveyor 21 may comprise a pair of endless belts respectively entrained about drive and idler pulleys and oriented so that the surfaces of the belts are in substantially contiguous relation so that each article is fed therebetween-the belts conveying the articles to the end of the conveyor while holding the flaps in their folded position to permit the adhesive to cure. Again, guide structure which may be in t e form of rollers will be included to positively direct articles from the drum 10 and onto the conveyor 21, but such structure has been omitted from the drawings for purposes of simplifying the same.

The flap-folding apparatus includes a pair of substantially similar and generally identical flap-folding units 22a and 22!) mounted in transversely spaced relation by cap screws or other suitable means upon a bracket 23 secured to the frame 24 of the bag-bottoming machine. Since the devices 22a and 2215 are identical in their essential function, a detailed description of the structural compositions thereof will be set forth only with reference to the unit 22a, although any differences between the two units will be specifically noted.

The flap-folding unit 22a, as shown most clearly in FIGURES 2 and 3, includes support structure in the form of a casing 25 defining therein a compartment 26 and having a removable cover or top wall 27 that may be secured in position by a plurality of cap screws 28. Rotatably supported in bearings 29 and 30 respectively mounted in openings provided therefor in the laterally spaced walls 31 and 32 of the casing is a drive shaft 33 equipped at one end thereof exteriorly of the casing with a gear 34 that is drivingly connected to the ring gear 12 of the drum 10 through an idler gear 35.

The bearing 29 is actually located within a hollow boss 36 that extends laterally outwardly from the casing side wall 31, and may be formed integrally therewith, and such bearing seats against a shoulder that constrains the bearing against movement in one axial direction along that shaft 33. Axial displacements of the bearing in the opposite axial direction are prevented by a stop 37 carried by the shaft 33. The gear 34 is located adjacent such stop and may be secured in any suitable manner to the shaft 33 so that relative movement therebetween is prevented, as by means of the split collar shown in FIGURE 2. The bearing 39 seats against a shoulder that prevents axial displacements in one direction, and is held against such shoulder by a lock ring 38 secured by cap screws 39 to the wall 32 of the casing. A stop, which may be in the form of a nut 40 threaded onto the shaft 33, positively locates (in conjunction with the stop 37) the shaft 33 with respect to the casing 25, and these two stops constrain the shaft against displacements in either axial direction.

Mounted upon the shaft 33 in a substantially central position within the compartment 26 is a helical gear 41 that is rotatable with the shaft. The gear 41 meshes with a helical gear 42 keyed to a stub shaft 43 that is rotatably supported at its opposite ends by bearings 44 and 45-the first of which is mounted in a depending bracket 46 provided by the casing 25 within the compartment 26, and the latter of which is supported in a mounting plate 47 secured to the rear wall 48 of the casing. The bearing 45 seats against a shoulder provided therefor by the mounting plate 47, and is pressed thereagainst by a cover plate 49 that overlies the mounting plate 47 and is secured thereto by cap screws 50 which also serve to secure both of the plates 47 and 49 to the wall 48 of the casing. A cap screw 51 threaded into a tapped opening in the shaft 43 secures a stop 52 to the end of the shaft, and the stop overlies the inner race of the bearing 45 and thereby prevents axial displacement of the shaft 43 toward the left, as viewed in FIGURE 3.

The axial position of the gear 42 along the shaft 43 is determined by a pair of tubular spacers 53 and 54 coaxially mounted on the shaft 43 and respectively disposed on opposite sides of the gear 42. The spacer 53 bears at one end against the gear and at its other end against the inner race of the bearing 45, while the spacer S4 bears against the opposite side of the gear 42 and the inner race of the bearing 44. At its inner end, the shaft 43 is equipped with a driver 55 which is adjacent the bearing 4-4 and thereby prevents axial displacements of the shaft 43 in the opposite direction, or toward the right as viewed in FIGURE 3.

The driver 55 is secured to the shaft 43 so as to rotate therewith, and is oriented so that it is substantially normal to the axis of rotation of the shaft 43 and extends radially outwardly therefrom in one direction, as shown most clearly in FIGURE 4. The driver 55 is provided with a radially disposed channel or recess 55 extending substantially from the longitudinal axis of the shaft 43 to the outer extremity of the driver. Located within the channel 56 is a roller 57 that is movable along the length of the channel and, therefore, is radially displaceable with respect to the shaft 43 and axis of rotation defined thereby. The roller 57 comprises a part of a crank 58 which includes a shaft journalled for rotation in bearings 59 and 65) that are supported by a mounting plate 61 secured by cap screws 62 to the wall 63 of the casing 25. The inner bearing seats against a shoulder provided therefor by the mounting plate 61, the outer bearing 59 is separated from the inner hearing by an annular spacer 64, and both bearings are locked within the plate 61 by a retainer ring 65 that bears against the outer race of the bearing 59 and is secured to the plate 61 by screws 66.

The roller 57 forms the throw or arm of the crank 53 and is offset from the axis of rotation thereof so that it defines by its movement a rotary path of generally cylindrical configuration coaxial with the axis of rotation of the crank. The roller is secured to the main structure of the crank by a nut that is threadedly received on an end portion of the roller stem which extends through an opening provided therefor in the laterally extending arm portion 67 of the crank. An enlarged shoulder provided by the crank 58 seats against the bearing 60 and prevents axial displacements of the crank in one direction. A split washer or snap ring 68 mounted on the crank 58 is located adjacent the bearing 59 and prevents axial movement of the crank in the opposite direction. The crank 58 extends outwardly from the casing and, in particular, beyond the retainer ring 65; and secured to the outer end portion of the crank so as to rotate therewith is a flap folder 69a. The flap folder may be locked upon the shaft by any suitable means as, for example, a split collar 70 as illustrated in the drawings.

As stated hereinbefore, the structural composition of the unit 2212 is essentially the same as that of the unit 22a except that the gears respectively corresponding to the gears 41 and 42 will be selected and arranged so that the flap folder 69b rotates in a direction opposite to that of the [lap folder 6%, as is indicated by the arrows in FIGURE 2. The unit 22b is driven by the unit 22a, and the two units are drivingly connected through a shaft 71 (which may be integral with the shaft 33 or a separate shaft fixed thereto) and a coupling 72 that may be a conventional chain coupling equipped with tapered bushings to permit initial adjustment of the acceleration mechanism. Thus, the two units are simultaneously energized and, consequently, the flap folders 6% and 6% are synchronously rotated.

Before describing the operation of the flap-folding device, and since it is illustrated in operative association with a bag-bottoming machine, the characteristics of a typical bag, such as the familiar self-opening paper grocery bag shown in FIGURES 5 through 7, should be considered. The bag or bag tube shown in FIGURE 5 is identified with the numeral 73, and has the configuration illustrated when delivered to the drum it In this form, the longitudinal edge portions 74 and 75 of the bag bottom have been folded inwardly, and the bag bottom has an outer leading flap 76 and an outer trailing flap 77. A pattern of adhesive 73 is applied to the bag bottom by the adhesive applicator 16, and the leading and trailing flaps are adapted to be folded from their open to their closed position as the bag tube is advanced, in the direction of the arrow, along its longitudinal axis and through an arcuate path defined by the cylindrical surface of the drum 10. As the bag tube 73 is advanced by the drum, the outer trailing flap 77 is first folded toward the bag bottom or plane of the bag and against the underlying inner flaps 74 and 75 by the flap folders 6% and 69b; and subsequent thereto, the outer leading flap 76 is folded toward the bag bottom or plane of the bag by a stationary flap-folding plow 79. FIGURE 7 illustrates the bag after the bottom thereof has been completely closed; and to dilferentiate the completed bag from the bag tube 73, it is designated with the numeral 80.

In operation of the total apparatus illustrated in FIGURE 1, a succession of bag tubes 73 is fed to the drum It) from the conveyor and since the drum is being rotated by the motor 14 and drive gear 13, each bag tube is continuously advanced to and through the adhesive-applying station where the adhesive applicator 16 applies the adhesive pattern 7% to the bottom of the bag tube. The applicator 16 is rotated in timed relation with the drum 10 since it is driven thereby through the ring gear 12 and gear 19. The bag tubes are then advanced to and through the bagclosing station whereat the flap folders 6% and 69b fold the outer trailing flap 77 into adhesively-gripped relation with the underlying portions of the bag bottom, and thereafter the outer leading flap 76 is folded to its closed position by the plow 79 and is adhesively secured to the flap 77 and other 55 underlying portions of the bag bottom. Each bag is then discharged to the conveyor 21 which carries the bags to subsequent stations along the bag-forming line.

Since the flap-folding device is driven by the ring gear 12 of the drum 10 through the idler gear 35 and gear 34, the device functions in timed relation with the rotational movement of the drum; and because the two units 22a and 2212 are driven through what may properly be considered a common shaft and the gear 34 secured thereto, the flap folders 69a and 6912 are synchonously rotated. As the gear 34 is rotated, the shaft 33 is rotated and the gear 41 is necessarily rotated since it is fixedly secured to the shaft 33. Rotation of the gear 41 causes the gear 42 to rotate, whereupon the shaft 43 is caused to rotate since it is keyed to the gear 42. As a result, the driver 55 rotates which causes the crank 53 to rotate about its axis because of its connection with the driver 55 through the crank arm or roller 57. Thus, the flap folder 6% is rotated.

It should be noted that the axis of rotation of the driver 55, which is the same as the axis of rotation of the shaft 43, is substantially parallel to the axis of rotation of the crank 58 and is offset therefrom in a vertical direction. In the particular embodiment illustrated, it is not offset in either transverse direction. As a consequence, the crank arm or roller 57 is continuously displaced in radial directions with respect to the axis of rotation of the driver as the driver rotates, and the radial distance of the crank arm from the axis of the driver at any instant is determined by the angular position of the driver.

It is clear that the driver 55 must be rotated at a substantialy constant angular velocity since it is driven by the motor 14 through determinant gearing; however, the angular velocity of the chank 58 will continuously vary since its velocity at any instant is determined by the distance of the crank arm or roller 57 from the axis of rotation of the driver 55. The radial distance of the roller 57 from the rotational axis of the driver will continuously vary from the minimum, shown in FIGURE 3 and by full lines in FIGURE 4, to a mammum illustrated by the broken lines in FIGURE 4. Accordingly, the crank 58 will have a varying velocity pattern in which it is accelerated as the roller 57 moves from its innermost to its outermost position along the channel 56 and is decelerated as the roller moves along the channel in the opposite direction.

It may be noted that the axis of rotation of the crank 58, and therefore of the flap folder 69a secured thereto, is spacially fixed; and as the flap folder 69a rotates, it describes a single continuous circular or cylindrical plane, and such plane is substantially tangent to the cylindrical surface of the drum lit). That is to say, the flap folder or plane defined by its rotation need not actually touch the surface of the drum, and in fact should be spaced slightly therefrom so as to accommodate the thickness of a bag tube 73 disposed therebetween; but for purposes of properly orienting the plane described by the flap folder, a condition of substantial tangency may be assumed.

It may be noted, as shown most clearly in FIGURES 2 and 6, that a portion of the arcuate path or plane described by each of the flap folders extends over the drum It at the folding station therealong; and in particular, ex tends over the bag tube '73 and must be sufficiently close to the path of movement thereof that the trailing flap 77 of each such bag is engaged by the flap holders and is folded thereby into closed position. Further, the flap folders to effect such folding engagement must travel in the same general direction as the bag and drum it} during engagement with the flap, and the peripheral or linear velocity of the flap folders at such time must be greater than that of the bag in order that the flap folders overtake the flap and fold the same forwardly as the bag is being continuously advanced by the drum.

Accordingly, the crank arm 57 and flap folder 6% are oriented with respect to each other so that the flap folder is accelerated as it moves in the direction toward engagement with the bag fiap and is decelerated subsequent thereto. More particularly, the flap folders are accelerated to a maximum velocity when they are extending inwardly as shown by the dot-and-dash lines designated with the letter x in FIGURE 4, and are decelerated to their minimum velocity at approximately 180 therefrom, as shown by the broken lines designated with the letter y in FIGURE 4. In FIGURE 4, the broken lines y correspond to the full-line showing of the driver 55 and roller 57, while the dot-and-dash lines at correspond to the phantom showing of the driver and roller.

Although the flap folders 6% and 69b have a varying velocity pattern of angular acceleration for approximately one-half of each cycle of rotation thereof and of angular deceleration for approximately the remaining one-half of each such cycle, the average angular velocity thereof corresponds to the rate at which bags are advanced into the folding station by the drum it) so that a bag flap is engaged during each complete rotation of the flap folders. An important advantage of the varying velocity pattern is that the flap folders can have a generally linear velocity at the time they are approaching the trailing flap of each bag sufficient to overtake the same; but on the other hand, the circle described by the rotational movement of each flap folder can have a relatively small diameter. In the absence of the varying velocity pattern, the diameter of the described circular path would necessarily be much greater in order to provide the requisite linear velocity at the time of flap engagement and the requisite angular velocity to time the flap folders with the advancement of successive bags into the folding station. As a result, the over-all dimensions of the flap-folder device can be quite small, which permits the device to be used in close confines.

The fiap folders 69a and 6% are flat along their planar outer end portions and are relatively wide which increases the period of their engagement with each trailing fiap 77. Further, each flap folder progressively increases in width from a narrow inner end portion to a wide outer end portion and accordingly, a relationship exists between the width of the flap folder at any point therealong and the linear or peripheral velocity of the flap folder at the corresponding point such that each location along the length of the flap folder tends to be maintained in contact with the flap 17 for a generally similar length of time, whereby a firm adhesive engagement of the flap with the underlying bag bottom is obtained across the entire flap.

The flap folders, upon engagement thereof with the outer trailing flap 77, fold the same forwardly toward the bag bottom and wipe across the flap from the center or an intermediate portion thereof toward the outer longitudinal edge portions and progressively press increasingly larger portions of the folded flap into adhesive engagement with the portions of the bag bottom underlying the same. Thus, an especially advantageous method is employed for closing the bag bottoms since such wiping action by the wide, fiat folders along the path of movement of the bag tube presses the trailing fiap firmly against the bag bottom and tends to squeeze out wrinkles, air pockets and other irregularities that would otherwise cause an imperfect bag closure.

Since each compartment 26 is closed and the relatively movable components of the apparatus are located within one or the other of these compartments, such components may have a bathed in oil lubrication because each compartment serves as a closed lubrication reservoir. This not only reduces the requirement for manual attention in that the lubricant need be changed only infrequently, but assures proper and complete lubrication of the various parts and thereby increases the life thereof. The apparatus is readily adapted to various bag machine sizes in that the only change ordinarily required is an alteration in the spacing between the units 22a and 22b,

which is conveniently accommodated by changing the shaft 71 for one of appropriate length.

While in the foregoing specification an embodiment of the invention has been set forth in considerable detail for purposes of making an adequate disclosure thereof, it will be apparent to those skilled in the art that numerous changes may be made in such details without departing from the spirit and principles of the invention.

I claim:

1. In bag-bottoming apparatus, a generally cylindrical bag-bottoming drum adapted to be continuously driven for consecutively advancing through adhesive-applying and flap-folding stations a succession of bags each of which has an outer leading flap and an outer trailing flap to be folded from open to closed position, and structure for folding each such trailing flap comprising a flap folder rotatably mounted for movement about a generally circular path describing a plane having at least a portion thereof overlapping the cylindrical surface of said rotatable drum at such folding station and being sufficiently close to such surface that the trailing fiap of a bag at such folding station is engaged by said flap folder and folded thereby from open to closed position, such described plane being oriented in substantially tangential relation with respect to the cylindrical surface of said drum and the direction of rotation of said flap folder during engagement thereof with such trailing flap at such folding station being generally along the direction of rotation of said drum, and drive mechanism connected with said flap folder for continuously rotating the same with a varying velocity pattern of angular acceleration immediately prior to and during a substantial portion of its engagement with such trailing flap and of angular deceleration subsequent thereto, the axis of rotation of said flap folder being spacially fixed and said flap folder having a narrow inner end portion and a wide outer end portion relative thereto and progressively increasing in width from said narrow to said wide end portion so as to approximate a condition of general similitude as to the width-linear velocity relationship of all successive segments along the length of said fiap folder so that all such segments tend to remain in engagement with such trailing flap for approximately equal periods of time irrespective of the distances of the successive segments from said axis of rotation.

2. In bag-bottoming apparatus, a generally cylindrical bag-bottoming drum adapted to be rotatably driven for advancing along a path defined in part by the cylindrical surface thereof and through adhesive-applying and flapfolding stations a succession of bags each of which has at the bottom end thereof an outer leading flap and an outer trailing flap both of which are to be folded from open to closed position, and structure for folding each such trailing flap comprising a substantially rigid flap folder supported with respect to a spacially fixed axis for rotation thereabout along a closed arcuate path the outer annulus of which is traced by the outer end portion of said flap folder and describes a fixedly located plane at least a portion of which overlaps the cylindrical surface of said rotatable drum at such folding station and is sufficiently close to such surface that the trailing flap of a bag at such folding station is engaged by said flap folder and is folded thereby from open to closed position, such described plane being defined in part by a line essentially parallel to the axis of rotation of said bag-bottoming drum and such plane being oriented along a tangent to the cylindrical surface of said bag-bottoming drum at the flap-folding station, the direction of rotation of said flap folder during engagement thereof with any such trailing flap at such folding station being generally along the direction of movement thereat of the cylindrical surface of said drum, and drive mechanism connected with said flap folder for rotating the same at an average angular velocity related to the rate of advancement of bags into such closing station by said bag-bottoming dum so that the trailing flap of each successive bag is engaged by said flap folder and is folded thereby from open to closed position, the linear velocity of said fiap folder adjacent the outer end portion thereof being greater than the linear velocity of each bag during engagement of the trailing flap thereof by said flap folder in order that the flap folder be effective to displace each such trailing flap forwardly from the open toward the closed position thereof.

3. The apparatus of claim 2 in which said drive mechanism comprises means for rotating said flap folder with a varying velocity pattern for angular acceleration immediately prior to and during a substantial portion of its engagement with such trailing flap and of angular deceleration subsequent thereto.

4. The apparatus of claim 2 in which said flap folder has a narrow inner end portion adjacent the aforesaid axis of rotation thereof and a relatively wide outer end portion and progressively increases in width from said narrow to said wide end portion so as to approximate a condition of general similitude as to the width-linear velocity relationship of all succesive segments along the length of said flap folder so that all such segments tend to remain in engagement with such trailing flap for approximately equal periods of time irrespective of the distances of the successive segments from the axis of rotation of said flap folder.

5. In bag-bottoming apparatus, a generally cylindrical bag-bottoming drum adaptedto be rotatably driven for advancing along a path defined in part by the cylindrical surface thereof and through adhesive-applying and flapfolding stations a succession of bags each of which has at the bottom end thereof an outer leading flap and an outer trailing flap both of which are to be folded from open to closed position, and structure for folding each such trailing flap comprising a pair of substantially rigid flap folders respectively associated with a pair of substantially parallel and specially fixed axes, each of said flap folders being supported with respect to its associated axis for rotation thereabout along a closed arcuate path the outer annulus of which is traced by the outer end portion of the associated flap folder and describes a fixedly located plane at least a portion of which overlaps the cylindrical surface of said rotatable drum at such folding station and is sufficiently close to such surface that the trailing flap of a bag at such folding station is engaged by each of said flap folders and is folded thereby from open to closed position, the paths traced by said flap folders being disposed in side by side relation and the respectively described planes being substantially common and being defined in part by a line essentially parallel to the axis of rotation of said bag-bottoming drum and being oriented along a tangent to the cylindrical surface of said bagbottoming drum at the flap-folding station, said flap folders being rotatable in opposite directions but with the directions of rotation thereof during engagement with any such trailing flap at such folding station being generally along the direction of movement thereat of the cylindrical surface of said drum, and drive mechanism connected with each of said flap folders for rotating the same at an average angular velocity related to the rate of advancement of bags into such closing station by said bagbottoming drum so that the trailing flap of each successive bag is engaged by said flap folders and is folded thereby from open to closed position, the linear velocity of each of said flap folders adjacent the outer end portions thereof being greater than the linear velocity of each bag during engagement of the trailing flap thereof by said flap folders in order that the flap folders be effective to displace each such trailing fiap forwardly from the open toward the closed position thereof.

6. The apparatus of claim 5 in which each of said flap folders has a fiat outer end portion, and enlarges in width toward its outer end from a relatively narrow inner end portion adjacent its associated axis of rotation.

7. The apparatus of claim 5 in which said drive mechanism comprises means for rotating each of said flap folders with a varying velocity pattern of angular acceleration immediately prior to and during a substantial portion of its engagement with such trailing flap and of angular deceleration subsequent thereto, and in which each of said flap folders has a narrow inner end portion adjacent its associated axis of rotation and a relatively wide outer end portion and progressively increases in width from said narrow to said wide end portion so as to approximate a condition of general similitude as to the width-linear velocity relationship of all successive segments along the length thereof so that all such segments tend to remain in engagement with such trailing flap for approximately equal periods of time irrespective of the distances of the successive segments from the related axis of rotation.

8. Structure for use with bag-bottoming apparatus having a generally cylindrical bag-bottoming drum adapted to be rotatably driven for advancing along a path defined in part by the cylindrical surface thereof and through adhesive-applying and flap-folding stations a succession of bags each of which has at the bottom end thereof an outer leading flap and an outer trailing flap both of which are to be folded from open to closed position, comprising a flap folder supported for rotation along a closed arcuate path at least a portion of which is adapted to overlap the cylindrical surface of such rotatable drum at the folding station in suficiently close proximity to such surface that the trailing flap of a bag at the folding station is engaged by said flap folder and is folded thereby from open to closed position, and drive mechanism connected with said flap folder for rotating the same along such arcuate path to enable the flap folder to engage the trailing flap of each succesive bag advanced into such flap folding station and fold each such flap from the open toward the closed position thereof, said flap folder having a narrow inner end portion and a Wide outer end portion and progressively increasing in width from said narrow to said wide end portion so as to approximate a condition of general similitude as to the width-linear velocity relationship of all succesive seg ments along the length of said flap folder so that all such segments tend to remain in engagement with a flap being folded for approximately equal periods of time irrespective of the distances of the successive segments from the axis of rotation of the flap folder.

References Cited in the file of this patent UNITED STATES PATENTS 807,211 Smith Dec. 12, 1905 820,678 Stone May 15, 1906 1,893,285 Hunziker Jan. 3, 1933 2,691,329 Evers Oct. 12, 1954 FOREIGN PATENTS 718,123 France Oct. 27, 1931 

1. IN BAG-BOTTOMING APPARATUS, A GENERALLY CYLINDRICAL BAG-BOTTOMING DRUM ADAPTED TO BE CONTINUOUSLY DRIVEN FOR CONSECUTIVELY ADVANCING THROUGH ADHESIVE-APPLYING AND FLAP-FOLDING STATIONS A SUCCESSION OF BAGS EACH OF WHICH HAS AN OUTER LEADING FLAP AND AN OUTER TRAILING FLAP TO BE FOLDED FROM OPEN TO CLOSED POSITION, AND STRUCTURE FOR FOLDING EACH SUCH TRAILING FLAP COMPRISING A FLAP FOLDER ROTATABLY MOUNTED FOR MOVEMENT ABOUT A GENERALLY CIRCULAR PATH DESCRIBING A PLANE HAVING AT LEAST A PORTION THEREOF OVERLAPPING THE CYLINDRICAL SURFACE OF SAID ROTATABLE DRUM AT SUCH FOLDING STATION AND BEING SUFFICIENTLY CLOSE TO SUCH SURFACE THAT THE TRAILING FLAP OF A BAG AT SUCH FOLDING STATION IS ENGAGED BY SAID FLAP FOLDER AND FOLDED THEREBY FROM OPEN TO CLOSED POSITION, SUCH DESCRIBED PLANE BEING ORIENTED IN SUBSTANTIALLY TANGENTIAL RELATION WITH RESPECT TO THE CYLINDRICAL SURFACE OF SAID DRUM AND THE DIRECTION OF ROTATION OF SAID FLAP FOLDER DURING ENGAGEMENT THEROF WITH SUCH TRAILING FLAP AT SUCH FOLDING STATION BEING GENERALLY ALONG THE DIRECTION OF ROTATION OF SAID DRUM, AND DRIVE MECHANISM CONNECTED WITH SAID FLAP FOLDER FOR CONTINUOUSLY ROTATING THE SAME WITH A VARYING VELOCITY PATTERN OF ANGULAR ACCELERATION IMMEDIATELY PRIOR TO AND DURING A SUBSTANTIAL PORTION OF ITS ENGAGEMENT WITH SUCH TRAILING FLAP AND OF ANGULAR DECELERATION SUBSEQUENT THERETO, THE AXIS OF ROTATION OF SAID FLAP FOLDER BEING SPACIALLY FIXED AND SAID FLAP FOLDER HAVING A NARROW INNER END PORTION AND A WIDE OUTER END PORTION RELATIVE THERETO AND PROGRESSIVELY INCREASING IN WIDTH FROM SAID NARROW TO SAID WIDE END PORTION SO AS TO APPROXIMATE A CONDITION OF GENERAL SIMILITUDE AS TO THE WIDTH-LINEAR VELOCITY RELATIONSHIP OF ALL SUCCESSIVE SEGMENTS ALONG THE LENGTH OF SAID FLAP FOLDER SO THAT ALL SUCH SEGMENTS TEND TO REMAIN IN ENGAGEMENT WITH SUCH TRAILING FLAP FOR APPROXIMATELY EQUAL PERIODS OF TIME IRRESPECTIVE OF THE DISTANCES OF THE SUCCESSIVE SEGMENTS FROM SAID AXIS OF ROTATION. 